Question

How many milliliters of boiling water are required to dissolve 26.78g of phthalic acid? Show work.

If this solution were cooled to 14 degrees celcius, how many grams of phthalic acid would crystallize out? show work.

Answer 1

You need the solubility data given on textbook tables for 100ml of water. Research says us that we need 18 gr of phthalic acid to dissolve 100ml of water. So we can now find volume for 26.78 gr.

The solubility of phthalic acid in boiling water will be 26.78 gr / Volume (ml) = 26.78 gr/ V x 18gr/100ml

V = 26.78 gr x 100 ml / 18 gr = 148.78 ml of boiling water.

Now at 14°C textbooks refers the solubility at 0.54 gr/100 ml

The Weight og Phthalic acid will remain at 14°C

W (gr) / 148.78 ml x 0.54 gr/ 100 ml

W = 148.78 ml x 0.54 gr/ 100 ml = 0.8034 gr

The required mass to cristalize phthalic acid will be = 26.78 gr - 0.8034 gr = 25.97 gr

Hope it helps!